Thrust augmenting expansion engine

ABSTRACT

An expansion engine capable of extracting energy from an expanding gas and distributing that energy between the gas and a fluid stream to generate a propulson or power force. The engine includes a thrustor mounted for rotation about a shaft and consisting of a hub and a concentric shroud connected by a number of evenly spaced, helical vanes. The vanes divide the annular space between the hub and shroud into equal sized helical channels which are open at both ends. The forward ends of the channels are open during a portion of the rotation and closed during a second portion of the rotation. The channels are filled with fluid when in the unobstructed position, and an expandable gas is delivered behind each slug of fluid in the channel when in the obstructed position. The high pressure gas accelerates the already moving water to the rear of each channel.

United States Patent [191 Zovko Jan. 8, 1974 1 THRUST AUGMENTING EXPANSION ENGINE [76] Inventor: Carl T. Zovko, 302 Penwood Rd.,

Silver Spring, Md. 20901 [22] Filed: Jan. 23, 1968 [21] Appl. No.: 701,813

Primary ExaminerBenjamin Borchelt Assistant ExaminerThomas 1-1. Webb Attorney-J. P. Dunlavey, J. O. Tresansky and S. P. Fisher [5 7] ABSTRACT An expansion engine capable of extracting energy from an expanding gas and distributing that energy between the gas and a fluid stream to generate a propulson or power force. The engine includes a thrustor mounted for rotation about a shaft and consisting of a hub and a concentric shroud connected by a number of evenly spaced, helical vanes. The vanes divide the annular space between the hub and shroud into equal sized helical channels which are open at both ends. The forward ends of the channels are open during a portion of the rotation and closed during a second portion of the rotation. The channels are filled with fluid when in the unobstructed position, and an expandable gas is delivered behind each slug of fluid in the channel when in the obstructed position. The high pressure gas accelerates the already moving water to the rear of each channel.

26 Claims, 10 Drawing Figures PATENTED 81974 3.783.814

SHEET 1 [IF 4 Carl Thomas Zovko INVENTOR ATTOR 1 THRUST AUGMENTING EXPANSION ENGINE BACKGROUND OF THE INVENTION This invention relates generally to an expansion engine and more particularly to a thrust augmenting expansion engine.

There has been a long felt need for a reliable, simple, efficient, compact, low maintenance expansion engine. Expansion engines have been used in the past as prime movers for providing power, and as propulsion systems for underwater, water surface and air vehicles. In each of these embodiments various problems have arisen which heretofore have gone unsolved or have been solved at the expense of creating some other problem less important in that particular application. For example, propeller driven underwater propulsion systems for torpedoes become very inefficient at speeds above seventy knots. Much of the loss occurs because the force between the propeller blades and the water is not parallel to the vehicle velocity. This causes much of the shaft power to be wasted in giving a rotational velocity to the water. Propellersoften cavitate at high speeds which causes a drastic drop in propeller efficiency. Much effort has been spent towards developing direct thrust propulsion devices which would avoid the losses mentioned above. A rocket is such a direct thrust device. However, a rocket is inefflcient in the abovementioned applications because of its high exhaust. Therefore, propeller driven underwater vehicles although having a long range must travel at slow speed, while rockets attain highspeeds but are only useful for a short range and require a large part of the underwater vehicles volume for fuel storage. Thus, both propeller and rocket propulsion devices have been found not to be wholly successful for torpedo propulsion.

Both propeller and jet pump propulsion systems have been used in the past for water surface vehicles, but here again each system has its own distinct disadvantages. Propeller driven surface vessels cannot operate in shallow water, since vegetation tends to clog and bind the propellers. Furthermore, propeller driven surface vehicles are very inefficient at high speeds. Prior art jet pumps can be used at high speeds, but heretofore have been burdensomely large, extremely-expensive experience severe maintenance problems and mustbe manufactured of expensive exotic materials.

Aircraft engines of the propeller, pulse jet, and turbo jet type have all been used in the past, each with some degree of success. Propeller driven aircraft are limited inherently to low speeds, and are mechanically complex thus tending to create severe maintenance problems. Pulse jets are extremely inefficient, and are entirely too large for the amount of thrust developed. Furthermore, pulse jets experience take-off problems due to low initial thrust, and the exotic valving utilized creates severe maintenance problems. Turbo jets, perhaps the most successful, have been found to be extremely expensive because of the exotic materials necessary to cope with the high speeds of rotation and high temperatures.

Radial flow thrust augmenting engines have been proposed, but these devices experience serious centrifugal force and cavitation problems.

SUMMARY OF THE INVENTION Accordingly, one object of this: invention is to provide a new and improved low cost thrust augmenting expansion engine which is compact and efficient.

Another object of the invention. is the provision of a new and improved axial flow thrust augmenting expansion engine.

Still another'object of the present invention is to provide a new and improved axial flow thrust augmenting expansion engine which utilizes few moving parts to provide a continuous output.

A still further object of this invention is the provision of a new and improved multichannel axial flow expansion engine to propel a long range: high speed torpedo.

Another still further object of the instant invention is the provision of a new and improved long range, high speed torpedo which is capable of carrying a large payload.

Still another further object of the instant invention is to provide a new and improved torpedo propulsion sys' tern which is capable of long range propulsion at high speed utilizing an axial flow thrust augmentation device.

Still another object of the instant invention is to provide a new and improved water surface vehicle propul sion system which is capable of operation in shallow and/or weed infested waters.

Still another further object of the instant invention is the provision of an efficient low cost water surface ship expansion engine which is capable of weed ingestion.

Still another further object of the instant invention is to provide a new and improved axial flow aircraft expansion engine which has a high efficiency and can be manufactured at a low cost.

Another still further object of the instant invention is the provision ofa new and improved thrust augmenting axial flow aircraft expansion engine which is simple in construction and requires little maintenance.

One other object of this invention'is the provision of a new and improved turbine which fills the volume between the turbine blades with a fluid prior to introduction of an expandable gas while preventing radial escape of the fluids from the turbine.

Still one other object of this invention is the provision of a new and improved turbine which fills the volume between the turbine blades with a fluid prior to introduction of an expandable gas and subsequently permits the exit momentum of the fluid to be utilized for supplying the turbine with fluid at the inlet portion.

Briefly, in accordance with one embodiment of this invention, these and other objects are attained by providing an expansion engine having a rotatable member with inlet and exit protions supported on an axially extending shaft by an axially extending central hub with a plurality of equally spaced radially extending vanes secured about the periphery thereof at an angle to the shaft and extending from the inlet portion to the exit portion for forming a plurality of equally spaced circumferentially open ended channels. Provision is made for introducing a fluid into the inlet portion of at least one of the channels, and for substantially preventing fluid from escaping radially from all of the channels. Provision is also made for introducing an expandable gas into the inlet portion of at least one of the channels when that channel is filled with the fluid.

BRIEF DESCRIPTION OF THE DRAWINGS A more complete appreciation of the invention and many of the attendant advantages thereof will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is an exploded perspective view of a preferred embodiment of the invention showing the aft end of a torpedo and the propulsion unit therefor;

FIG. 2 is a cut-away perspective view of the thrust augmenting member of the propulsion unit of FIG. 1;

FIG. 3 is a side plan view of a second embodiment of the invention when used as a propulsion system for a water surface ship;

FIG. 4 is a sectional view along the line 44 of FIG.

FIG. 4a is a schematic representation of the cycle of the expansion engine of FIG. 4;

FIG. 5 is a side view, partially in section ofa third embodiment of the present invention in the form of an aircraft engine;

FIG. 6 is a sectional view along the line 6-6 of FIG.

FIG. 7 is a plan view of the aft end of the engine of FIG. 5;

FIG. 8 is a perspective view of a fourth embodiment of the present invention utilized as a turbine; and

FIG. 9 is a sectional view along the line 9-9 of FIG. 8.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings wherein like reference characters designate identical or corresponding parts throughout the several views, and more particularly to FIG. 1 thereof, a first embodiment of the present invention is shown as consisting essentially of a torpedo propulsion system mounted on the aft end of a torpedo body 10 having an axial shaft 12 affixed to and extending from the aft end of the torpedo body. A structureconically shaped rotatable thrust augmenting or thrustor member 14 is fixedly mounted on shaft 12 in abutting relationship with the rear surface 16 of the torpedo body 10. The rotatable thrustor 14 consists essentially of a central axial hub 18 and a concentric shroud 20 interconnected by a number of axially extending evenly spaced helical vanes 22, thus forming a plurality of equally spaced open ended peripheral channels 24. As can be clearly seen in FIGS. 1 and 2 the shroud 20 prevents fluid from escaping radially from the channels 24 while allowing fluid to freely pass through the open ends of the channels. When in the assembled position, the thrustor member 14 is held in positin on shaft 12 by a securing member 26 releasably attached to end 28 by conventional means such as screw threads, thus orienting the rotatable member 14 to have an inlet portion 30 adjacent surface 16 of the torpedo body 10 and an exit portion 32 at the rear thereof.

The aft end of torpedo body 10 is shaped to provide water channels 34 by reducing the outside diameter of the aft end of the torpedo to be equivalent to the outside diameter of the hub 18 such that water may freely pass into the channels 24 as the torpedo is propelled. The diameter of the torpedo between the water channels 34, at extended portions 36, is substantially equivalent to the abutting diameter of the shroud 20. Assuming the thrustor member 14 is rotating clockwise when viewed from the aft end of the torpedo, a plurality of diametrically spaced gas ports 38 are provided adjacent the leading edges 40 of the extended portions 36 in the aft end of the torpedo. In operation, water sequentially enters the helically shaped channels 24 when aligned with water channels 34. The channels 24 are thus filled with water by the time they reach the edges 40 of the extended portion 36. The gas ports 38 become aligned with the front opening of the channel immediately after the front opening is completely blocked by the extended portion 36. The gas ports 38 then admit high pressure gas to the channels. The particular source of high pressure gas is not part of the present invention and any conventional source of high pressure gas utilized in a torpedo may be used with this propulsion system. The high pressure gas accelerates the already moving water in the channels 24 toward the rear or exit portion 32. The volume within channels 24 available to the gas increases as the water moves to the rear but the gas pressure remains nearly constant while the front opening is aligned with the gas port 38. The inlet portion 30 of the channel remains blocked by the extended portion 36 for a time after passing the gas port. The high pressure gas in each channel continues to accelerate the water to the rear, and the gas pressure decreases as the volume increases. The cycle ends, and a new cycle starts, when the front opening of the channel passes thr extended portion 36 and is exposed to the next water channel 34 for filling with water again. At this time the gas pressure will have dropped to about the ambient pressure, and the water will be completely expelled. The thrust transmitted to the propelled vehicle is the force on the extended portions 36 of the aft end of the torpedo body 10 by the high pressure gas. The reaction force is the force on the water being accelerated to the rear. The rotatable member 14 may be in the shape of a frustrum vof a cone as shown in FIGS. 1 and 2 or the thrustor 14 may be cylindrical. The slight change in shape of the rotatable member 14 will not substantially alter the opening characteristics of the propulsion system.

The embodiment of the invention illustrated in FIGS. 3, 4 and 4a consists of the expansion engine utilized as a propulsion system for a water surface vehicle 100. In this embodiment, a thrust augmenting or thrustor member 102 is fixedly secured to a shaft 104 which in turn is mounted for rotation in bearings 106 on the water surface vehicle. The thrustor 102 is basically the same as the thrustor member 14 of FIG. 1.

The thrustor consists of a hub 108 and a concentric shroud 110 interconnected by a number of axially extending evenly spaced helical vanes 112 defining a plurality of open ended axially extending helical channels 114 symmetrically arranged about the shaft 104. As can be seen more clearly in FIG. 4, a portion of the thrustor 102 is exposed to an influx of water to the channels 114. A fuel air mixture is introduced sequentially into the water filled channels by means of conduit 116 from a conventional carburetor 118, which in turn, may be fed with air under pressure by means of a blower 120 driven by shaft 104. The conduit 116 is shaped so as to have an opening abutting the inlet section of a number of channels 114 when the channels are filled with water.

Extending from the edge of the open end portion 122 of conduit 116 is a plate-like member 124 which seals off the forward portion of at least one channel prior to that channel becoming aligned with the open end 122 of conduit 116. A closureplate 126 abuts the inlet portion of thrustor 102 to seal off the inlet portions of channels 114 after the fuel-air mixture has been introduced into the channels. A conventional ignition device such as a spark plug 128 is provided within the plate 126 for igniting the fuel-air mixture within the channels as they rotate into alignment therewith.

A tube 130 terminating adjacent ignition device 128 and extending through plate 126 may be providedfor introducing a fuel other than the fuel-air mixture into the channels from a storage tank 132 to either supplement the fuel-air mixture provided through conduit 116 or to be used alone.

In order to vary the thrust of the expansion engine the end 122 of conduit 116 and integral plate 124 may be mounted for rotation about shaft 104 to slidingly rotate over plate 126, thus varying the size of the opening through which the fuel-air mixture enters into the channels 114. A conventional starter motor 134 and associated gearing 136 may be further provided for initiating rotation of shaft 104 and thus starting the engine into operation.

Referring specifically to FIG. 4a when viewed with FIG. 4, it can be seen that segment! represents the water intake and gas exhaust cycle, segment II represents the fuelair mixtureintake cycle, segment III represents the fuel-air mixture ignition cycle and segment lV represents the gas expansion and water exhaust cycle of the expansion engine.

Another embodiment of the expansion engine of the present invention particularly suitable for application as a propulsion system for an aircraft is illustrated in FIGS. 5, 6 and 7. ln this embodiment, a shaft 200, hub 202, helically extending vanes 204 and concentric shroud 206 are assembled as a unit to define a plurality of open ended symmetrically arranged helically extending channels 208. The shaft 200 is mounted for rotation within bearings 210 and 212 mounted on fixed members 214 and 216 each of which is fixed to a mount 218. Inlet member 214 is shaped so as to provide open sections 220 and air blocking sections 222. Assuming the vanes204 to be rotating in a clock-wise direction as viewed in FIG. 6 it can be seen that each channel 208 is filled with air when in alignment with open sections 220. When in this position fuel is sprayed across the open faces of channels 208 by nozzles 224 mounted on the leading edges of blocking members 222 and the thrust of the engine may be controlled by varying the nozzle pressure so as to cover a larger or smaller number of channels with fuel. As the channels pass into alignment with air blocking sections 222 the fuel is ignited by means such as sprak plugs 226. Air overflow passages 228 are provided in the inlet member 214 for allowing cooling air to pass about the rotating shroud 206. A single stage compressor 230 may be mounted on shaft 200 for rotation therewith thus providing air under pressure to the inlet of channels 208. Exit member 216 consists essentially of constricting members 232 for restricting the exit fluid flow from those channels containing expanding gases to convert the pressure head to a velocity head in a manner similar to a conventional convergent nozzle.

In the turbine application embodiment of the present invention illustrated in FIGS. 8 and 9, a shaft 300 is mounted fr rotation within bearings (not shown) so as to mount a substantially disc shaped member 302 for rotation therewith. Equally spaced about the periphery of disc 302 are a plurality of radially extending curved blades 304. Secured to the outer edges 306 of blades 304 is a band shaped shroud 308 enclosing the outer radial edges of the blades for defining a plurality of open ended channels 310 about the periphery of the disc shaped member 302. Stationary circular cover plates 312 and 314 are mounted adjacent to the respective flat surfaces of disc 302 to enclose the ends of channels 310. Inlets are provided through cover plate 312 as shown generally at 316 for sequentially introducing an expandable gas such as steam into the channels 310. Prior to introduction of steam through inlet 316 a fluid such as water is introduced into the channels by way of conduits 318 through cover-312. A reservoir 320 is provided to maintain a sufficient amount of water within the conduits 318 to efficiently fill the channels 310. Thus it can be seen that water fills the channels 310 by means of conduits 318, and as the conduits pass before steam inlets 316 the expanding steam forces the water out of the conduit 310 into an exit portion 322 of conduit 318. The conduit 318 is provided to take advantage of the momentum of the exiting fluid from the channels 310. The exit fluid from a channel 310.when in alignment with steam inlet 316 can thus be utilized to reenter the system through cover plate 312, thus imparting its momentum to blades 304. It is not necessary that conduits 318 be entirely enclosed but couldrather be open chutes merely directing the exit fluid from cover plate 314 back to cover plate 312.

It will be apparent from the foregoing disclosure that each of the various embodiments operates on the same basic principle of thrust augmentation wherein power from a high pressure gas being isentropically expanded to ambient pressure may be imparted to a slug of fluid thus increasing the overall thrust of the system.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

l. Anex'pansion engine for a torpedo body having a forward portion and a planar aft end comprising a shaft secured to and extending axially from the aft end of said torpedo body,

a rotatable member having an inlet portion and an exit portion,

said rotatable member further having an axially extending central hub rotatably supported on said shaft such that the inlet portion is in abutting relation with said planar aft end of said torpedo body,

a plurality of equally spaced radially extending vanes secured about the periphery ofsaid hub at an angle with the axis of said shaft and extending from said inlet portion to said exit portion for forming a plurality of equally circumferentially spaced open ended channels,

said aft end of said torpedo body having an outside diameter substantially equivalent tothe outside diameter of said channels,

said aft end having at least one section of reduced diameter substantially equivalent to the inside diamemeans for substantially preventing fluid from escaping radially'from said channels, and

means for introducing an expandable gas into the inlet portion of at least one of said channels when said channel is filled with said fluid.

2. An expansion engine according to claim 1 wherein said means for introducing an expandable gas into the inlet portion of at least one of said channels is at least one gas port in said aft end of said torpedo body in axial alignment with said channels in said rotatable member.

3. An expansion engine according to claim 2 wherein a plurality of symmetrically arranged sections of reduced diameter are provided on the aft end of said torpedo body each of which is substantially equivalent in diameter to the inside diameter of said channels, and a plurality of said ports, equal in number to said sections of reduced diameter, are provided in said aft end of said torpedo body in axial alignment with said channels in said rotatable member.

4. An expansion engine according to claim 3 wherein siad channels are decreasing in cross section from said inlet portion to said exit portion of said rotatable memher.

5. An expansion engine according to claim 3 wherein said central hub, said vanes and said means for substantially preventing fluid from escaping radially from said channels are constructed as a single unit so as to rotate together about said shaft.

6. An expansion engine comprising an axially extending shaft,

a rotatable member having an inlet portion and an exit portion,

said rotatablemember having an axially extending central hub supported on said shaft for rotation therewith,

a plurality of equally spaced radially extending vanes secured about the periphery of said hub at an angle with the axis of said shaft and extending from said inlet portion to said exit portion for forming a plurality of equally circumferentially spaced open ended channels,

means for introducing a fluid into the inlet portion of at least one of said channels,

means for substantially preventing fluid from escaping radially from said channels,

means for introducing an expandable gas into the inlet portion of at least one of said channels when said channel is filled with said fluid, and

means for rotating said shaft for starting said engine.

7. An expansion engine according to claim 6 wherein said engine is mounted at the aft end ofa water surface vessel, and

at least a portion of said inlet portion of said channels being exposed to direct influx of water below said water surface vessel.

8. An expansion engine according to claim 7 wherein said means for introducing an expandable gas into the inlet portion of said channel comprises a carburetor,

a conduit extending from said carburetor to the inlet portion of said channel for providing a fuel-air mixture to said channel when filled with water, and

means for igniting said fuel-air mixture.

9. An expansion engine according to claim 8 further comprising means for providing air under pressure to said carburetor, means for preventing said expandable gases from escaping through the inlet portion of said rotatable member.

10. An expansion engine according to claim 9 further comprising means for varying the thrust of said engine.

11. An expansion engine according to claim 10 further comprising means for providing a second source of expandable gas to said channel in alignment with said ignition means.

12. An expansion engine for an aircraft comprising an axially extending shaft,

a rotatable member having an inlet portion and an exit portion,

said rotatable member having an axially extending central hub supported on said shaft,

a plurality of equally spaced radially extending vanes secured about the periphery of said hub at an angle with the axis of said shaft and extending from said inlet portion to said exit portion for forming a plurality of equally circumferentially spaced open ended channels,

means for introducing air under pressure into the inlet portion of at least one of said channels,

means for substantially preventing air from escaping radially from said channels,

a plurality of fuel nozzles directed into said channels through said inlet portion for introducing fuel into the inlet portion of at least one of said channels when said channel is filled with air.

13. An expansion engine according to claim 12 further comprising means for varying the thrust of said engine.

14. An expansion engine according to claim 13 wherein said air introducing means comprises an air compressor rotatably mounted on said shaft forward of said inlet portion.

15. An expansion engine according to claim 14 further comprising means for allowing a portion of said air to bypass said rotatable member.

16. An expansion engine according to claim 15 further comprising means at the exit portion of said rotatable member for partially restricting fluid flow from said channels.

17. An expansion engine comprising an axially extending shaft,

a rotatable member having an inlet portion and an V exit portion,

said rotatable member having an axially extending central hub supported on said shaft,

a plurality of equally spaced radially extending vanes secured about the periphery of said hub at an angle with the axis of said shaft and extending from said inlet portion to said exit portion for forming a plurality of equally circumferentially spaced open ended channels,

means for introducing a fluid into the inlet portion of at least one of said channels,

means for substantially preventing fluid from escaping radially from said channels,

means for introducing an expandable gas into the inlet portion of at least one of said channels when said channel is filled with said fluid, and

conduit means communicating with and extending from said exit portion of at least one channel to the inlet portion of at least one preceding channel in the direction of rotation.

18. An expansion engine according to claim 17 wherein said rotatable member is affixed to said shaft, and further comprising means for extracting power from said shaft.

19. In combination with an underwater vehicle, a propulsion system comprising:

a' shaft'secured to and extending from the aft end of said vehicle,

an axially extending central hub mounted for rotation on said shaft in abutting relationship with said aft end of said vehicle,

radial vanes secured to said hub and helically extending about the'axis of said shaft,

a shroud secured to said vanes to form a plurality of axially extending open ended helical channels symmetrically arranged about the peripheral extent of said hub,

said aft end of said vehicle being so shaped as to permit water to enter only a portion of said helical channels, and

means on said aft end of said vehicle for rotating said hub.

20. The device of claim 19 wherein a portion of said aft end of said vehicle has an outside diameter substantially equivalent to the outside diameter of said channels, and at least one segment of said aft end of said vehicle has an outside diameter substantially equivalent to the inside diameter of said channels.

21. The device of claim 20 wherein said means for rotating said thrust augmenting member comprises at least one source of gas in said vehicle and a port in the aft end of said vehicle at the portion of maximum diameter for releasing said gas into said channels when filled with water.

22. The device of claim 21 wherein said channels are convergent in cross section.

23. An aircraft engine comprising a shaft rotatably mounted on said aircraft parallel to the axis of said aircraft,

a cylindrical thrust augmenting member mounted on said shaft and having a plurality of open ended channels symmetrically arranged about said shaft,

said channels helically extending about the axis of said shaft, means for blocking air from entering at least one segment of the forward end of said cylindrical member,

means on said blocking means for introducing fuel into the forward open end of said cylindrical member,

means on said blocking means for igniting said fuel,

means on said shaft forward of said blocking means for providing air under pressure to the forward open ends of said channels, and

bypass means for allowing a portion of said air under pressure to flow around the outer surface of said cylindrical member.

24. The aircraft engine of claim 23 further comprising means for restricting exit fluid flow through at least one segment of said cylindrical member.

25. An engine'comprising a rotatably mounted shaft,

a substantially disc-shaped member affixed to said shaft and having a plurality of equally spaced radially extending curved blades affixed to the periphery thereof, means enclosing the outer radial edges of said blades for defining a plurality of open ended channels about the periphery of said disc-shaped member,

first and second cover plates for enclosing said ends of said channels, means for introducing a fluid through said first cover plate into a selected number of said channels,

means for introducing an expandable gas through said first cover plate into a selected number of said channels when filled with said fluid, and

means for permitting said fluid to escape from said channels through said second cover plate while said expandable gas is being introduced into said channels.

26. The engine of claim 25 further comprising means for guiding said escaping fluid from said second cover plate to said first cover plate to pass therethrough into said channels. 

1. An expansion engine for a torpedo body having a forward portion and a planar aft end comprising a shaft secured to and extending axially from the aft end of said torpedo body, a rotatable member having an inlet portion and an exit portion, said rotatable member further having an axially extending central hub rotatably supported on said shaft such that the inlet portion is in abutting relation with said planar aft end of said torpedo body, a plurality of equally spaced radially extending vanes secured about the periphery of said hub at an angle with the axis of said shaft and extending from said inlet portion to said exit portion for forming a plurality of equally circumferentially spaced open ended channels, said aft end of said torpedo body having an outside diameter substantially equivalent to the outside diameter of said channels, said aft end having at least one section of reduced diameter substantially equivalent to the inside diameter of said channels, means for introducing a fluid into the inlet portion of at least one of said channels, means for substantially preventing fluid from escaping radially from said channels, and means for introducing an expandable gas into the inlet portion of at least one of said channels when said channel is filled with said fluid.
 2. An expansion engine according to claim 1 wherein said means for introducing an expandable gas into the inlet portion of at least one of said channels is at least one gas port in said aft end of said torpedo body in axial alignment with said channels in said rotatable member.
 3. An expansion engine according to claim 2 wherein a plurality of symmetrically arranged sections of reduced diameter are provided on the aft end of said torpedo body each of which is substantially equivalent in diameter to the inside diameter of said channels, and a plurality of said ports, equal in number to said sections of reduced diameter, are provided in said aft end of said torpedo body in axial alignment with said channels in said rotatable member.
 4. An expansion engine according to claim 3 wherein siad channels are decreasing in cross section from said inlet portion to said exit portion of said rotatable member.
 5. An expansion engine according to claim 3 wherein said central hub, said vanes and said means for substantially preventing fluid from escaping radially from said channels are constructed as a single unit so as to rotate together about said shaft.
 6. An expansion engine comprising an axially extending shaft, a rotatable member having an inlet portion and an exit portion, said rotatable member having an axially extending central hub supported on said shaft for rotation therewith, a plurality of equally spaced radially extending vanes secured about the periphery of said hub at an angle with the axis of said shaft and extending from said inlet portion to said exit portion for forming a plurality of equally circumferentially spaced open ended channels, means for introducing a fluid into the inlet portion of at least one of said channels, means for substantially preventing fluid from escaping radially from said channels, means for introducing an expandable gas into the inlet portion of at least one of said channels when said channel is filled with said fluid, and means for rotating said shaft for starting said engine.
 7. An expansion engine according to claim 6 wherein said engine is mounted at the aft end of a water surface vessel, and at least a portion of said inlet portion of said channels being exposed to direct influx of water below said water surface vessel.
 8. An expansion engine according to claim 7 wherein said means for introduciNg an expandable gas into the inlet portion of said channel comprises a carburetor, a conduit extending from said carburetor to the inlet portion of said channel for providing a fuel-air mixture to said channel when filled with water, and means for igniting said fuel-air mixture.
 9. An expansion engine according to claim 8 further comprising means for providing air under pressure to said carburetor, means for preventing said expandable gases from escaping through the inlet portion of said rotatable member.
 10. An expansion engine according to claim 9 further comprising means for varying the thrust of said engine.
 11. An expansion engine according to claim 10 further comprising means for providing a second source of expandable gas to said channel in alignment with said ignition means.
 12. An expansion engine for an aircraft comprising an axially extending shaft, a rotatable member having an inlet portion and an exit portion, said rotatable member having an axially extending central hub supported on said shaft, a plurality of equally spaced radially extending vanes secured about the periphery of said hub at an angle with the axis of said shaft and extending from said inlet portion to said exit portion for forming a plurality of equally circumferentially spaced open ended channels, means for introducing air under pressure into the inlet portion of at least one of said channels, means for substantially preventing air from escaping radially from said channels, a plurality of fuel nozzles directed into said channels through said inlet portion for introducing fuel into the inlet portion of at least one of said channels when said channel is filled with air.
 13. An expansion engine according to claim 12 further comprising means for varying the thrust of said engine.
 14. An expansion engine according to claim 13 wherein said air introducing means comprises an air compressor rotatably mounted on said shaft forward of said inlet portion.
 15. An expansion engine according to claim 14 further comprising means for allowing a portion of said air to bypass said rotatable member.
 16. An expansion engine according to claim 15 further comprising means at the exit portion of said rotatable member for partially restricting fluid flow from said channels.
 17. An expansion engine comprising an axially extending shaft, a rotatable member having an inlet portion and an exit portion, said rotatable member having an axially extending central hub supported on said shaft, a plurality of equally spaced radially extending vanes secured about the periphery of said hub at an angle with the axis of said shaft and extending from said inlet portion to said exit portion for forming a plurality of equally circumferentially spaced open ended channels, means for introducing a fluid into the inlet portion of at least one of said channels, means for substantially preventing fluid from escaping radially from said channels, means for introducing an expandable gas into the inlet portion of at least one of said channels when said channel is filled with said fluid, and conduit means communicating with and extending from said exit portion of at least one channel to the inlet portion of at least one preceding channel in the direction of rotation.
 18. An expansion engine according to claim 17 wherein said rotatable member is affixed to said shaft, and further comprising means for extracting power from said shaft.
 19. In combination with an underwater vehicle, a propulsion system comprising: a shaft secured to and extending from the aft end of said vehicle, an axially extending central hub mounted for rotation on said shaft in abutting relationship with said aft end of said vehicle, radial vanes secured to said hub and helically extending about the axis of said shaft, a shroud secured to said vanes to form a plurality of axially extending open ended helical channels symmetrically arraNged about the peripheral extent of said hub, said aft end of said vehicle being so shaped as to permit water to enter only a portion of said helical channels, and means on said aft end of said vehicle for rotating said hub.
 20. The device of claim 19 wherein a portion of said aft end of said vehicle has an outside diameter substantially equivalent to the outside diameter of said channels, and at least one segment of said aft end of said vehicle has an outside diameter substantially equivalent to the inside diameter of said channels.
 21. The device of claim 20 wherein said means for rotating said thrust augmenting member comprises at least one source of gas in said vehicle and a port in the aft end of said vehicle at the portion of maximum diameter for releasing said gas into said channels when filled with water.
 22. The device of claim 21 wherein said channels are convergent in cross section.
 23. An aircraft engine comprising a shaft rotatably mounted on said aircraft parallel to the axis of said aircraft, a cylindrical thrust augmenting member mounted on said shaft and having a plurality of open ended channels symmetrically arranged about said shaft, said channels helically extending about the axis of said shaft, means for blocking air from entering at least one segment of the forward end of said cylindrical member, means on said blocking means for introducing fuel into the forward open end of said cylindrical member, means on said blocking means for igniting said fuel, means on said shaft forward of said blocking means for providing air under pressure to the forward open ends of said channels, and bypass means for allowing a portion of said air under pressure to flow around the outer surface of said cylindrical member.
 24. The aircraft engine of claim 23 further comprising means for restricting exit fluid flow through at least one segment of said cylindrical member.
 25. An engine comprising a rotatably mounted shaft, a substantially disc-shaped member affixed to said shaft and having a plurality of equally spaced radially extending curved blades affixed to the periphery thereof, means enclosing the outer radial edges of said blades for defining a plurality of open ended channels about the periphery of said disc-shaped member, first and second cover plates for enclosing said ends of said channels, means for introducing a fluid through said first cover plate into a selected number of said channels, means for introducing an expandable gas through said first cover plate into a selected number of said channels when filled with said fluid, and means for permitting said fluid to escape from said channels through said second cover plate while said expandable gas is being introduced into said channels.
 26. The engine of claim 25 further comprising means for guiding said escaping fluid from said second cover plate to said first cover plate to pass therethrough into said channels. 